Dual-Power Transmission Device for a Twin-Rotor Helicopter

ABSTRACT

A dual-power transmission device includes: a first output shaft secured rotatably in a housing and having a first rotor coupling portion extending outwardly of the housing; a second output shaft disposed to surround the first rotor coupling portion, secured rotatably in the housing, and having a second rotor coupling portion extending outwardly of the housing; first and second bevel gears mounted respectively on the first and second output shafts; first, second and third thrust bearings for positioning the first and second bevel gears in the housing; and first and second input units respectively coupled to first and second power sources and each meshing with the first and second bevel gears.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a twin-rotor helicopter, more particularly to a dual-power transmission device for a twin-rotor helicopter.

2. Description of the Related Art

As shown in FIG. 1, a conventional twin-rotor helicopter includes upper and lower rotor devices 1, 2 that rotate in opposite directions. A transmission mechanism (not shown) is used to transmit power from a single engine (not shown) in order to drive rotation of the rotor devices 1, 2 in the opposite directions. It is noted that safe landing of the conventional twin-rotor helicopter is not possible in case of failure of the single engine.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide a dual-power transmission device for a twin-rotor helicopter, which can transmit power from two engines for driving rotation of upper and lower rotors of the twin-rotor helicopter.

According to this invention, a dual-power transmission device is adapted to be coupled to first and second power sources of a twin-rotor helicopter, and comprises a housing, first and second output shafts, first and second bevel gears, first, second and third thrust bearings, and first and second input units.

The first output shaft has a first gear mounting portion secured rotatably in the housing, and a first rotor coupling portion extending from the first gear mounting portion and outwardly of the housing. The first output shaft is rotatable about a first axis.

The second output shaft is disposed to surround the first rotor coupling portion of the first output shaft, and has a second gear mounting portion secured rotatably in the housing, and a second rotor coupling portion extending from the second gear mounting portion and outwardly of the housing. The second output shaft is rotatable about the first axis.

The first bevel gear is mounted on and is rotatable coaxially with the first gear mounting portion. The second bevel gear is mounted on and is rotatable coaxially with the second gear mounting portion.

The first thrust bearing is disposed between the housing and the first bevel gear. The second thrust bearing is disposed between the first and second gear mounting portions. The third thrust bearing is disposed between the housing and the second bevel gear. The first, second and third thrust bearings cooperate to position the first and second bevel gears in the housing such that the first and second bevel gears are spaced apart from each other along the first axis and form a gear meshing space therebetween.

The first input unit is secured to the housing, is rotatable about a second axis that intersects the first axis, is adapted to be coupled to the first power source, and has a first bevel gear section extending into the gear meshing space and meshing with the first and second bevel gears.

The second input unit is secured to the housing, is rotatable about the second axis, is adapted to be coupled to the second power source, and has a second bevel gear section extending into the gear meshing space and meshing with the first and second bevel gears.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:

FIG. 1 is a perspective view of a conventional twin-rotor helicopter; and

FIG. 2 is an assembled sectional view of the preferred embodiment of a dual-power transmission device for a twin-rotor helicopter according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 2, the preferred embodiment of a dual-power transmission device for a twin-rotor helicopter according to the present invention is shown to be adapted to be coupled to first and second power sources 200, 300, and comprises a housing 10, first and second output shafts 20, 30, first and second bevel gears 40, 50, first, second and third thrust bearings 60, 61, 62, first and second input units 70, 80, first, second and third needle bearings 90, 100, 110, first and second ball bearings 120, 121, and first and second one-way clutches 130, 140. The first and second power sources 200, 300 are two engines of the helicopter in this embodiment.

The housing 10 includes an upper housing part 11, a lower housing part 12, and an intermediate housing part 13 disposed between and coupled to the upper and lower housing parts 11, 12. The lower housing part 12 is formed with a first housing surface 14 disposed to confront the first bevel gear 40. The upper housing part 11 is formed with a second housing surface 15 disposed to confront the second bevel gear 50.

The first output shaft 20 has a first gear mounting portion 21 secured rotatably in the housing 10, and a first rotor coupling portion 22 extending from the first gear mounting portion 21 and outwardly of the housing 10 through the upper housing part 11. The first output shaft 20 is rotatable about a first axis (X). In this embodiment, the first gear mounting portion 21 has a diameter larger than that of the first rotor coupling portion 22, thereby configuring the first output shaft 20 with an annular shoulder 23 at a junction of the first gear mounting portion 21 and the first rotor coupling portion 22. The first gear mounting portion 21 is formed with a first gear mounting flange 24 that extends in radial outward directions relative to the first axis (X). In this embodiment, the first rotor coupling portion 22 of the first output shaft 20 is adapted for coupling to an upper rotor (not shown) of the twin-rotor helicopter.

The second output shaft 30 includes a tubular body 31 that is disposed to surround a major section of the first rotor coupling portion 22 of the first output shaft 20 and that has a second gear mounting portion 300 secured rotatably in the housing 10 and a second rotor coupling portion 301 extending from the second gear mounting portion 300 and outwardly of the housing 10 through the upper housing part 11. The second output shaft 30 is rotatable about the first axis (X). In this embodiment, the second gear mounting portion 300 has one end proximate to the annular shoulder 23 of the first output shaft 20 and formed with a second gear mounting flange 32 that extends in radial outward directions relative to the first axis (X). In this embodiment, the second rotor coupling portion 301 of the second output shaft 30 is adapted for coupling to a lower rotor (not shown) of the twin-rotor helicopter.

The first bevel gear 40 is mounted on the first gear mounting flange 24 of the first gear mounting portion 21 and is rotatable coaxially therewith. The second bevel gear 50 is mounted on the second gear mounting flange 32 of the second gear mounting portion 300 and is rotatable coaxially therewith.

The first, second and third thrust bearings 60, 61, 62 are disposed in the housing 10 such that adjacent ones of the same are spaced apart from each other along the first axis (X). The first thrust bearing 60 is disposed between the first housing surface 14 of the lower housing part 12 and the first bevel gear 40. The second thrust bearing 61 is disposed between the first and second gear mounting flanges 24, 32 of the first and second gear mounting portions 21, 300. The third thrust bearing 62 is disposed between the second housing surface 15 of the upper housing part 11 and the second bevel gear 50. The thrust bearings 60, 61, 62 cooperate to position the first and second bevel gears 40, 50 in the housing 10 such that the first and second bevel gears 40, 50 are spaced apart from each other along the first axis (X) and form a gear meshing space 600 therebetween.

The first input unit 70 is secured to the housing 10, is rotatable about a second axis (Y) that intersects the first axis (X), is adapted to be coupled to the first power source 200, and has a first bevel gear section 71 extending into the gear meshing space 600 and meshing with the first and second bevel gears 40, 50. In this embodiment, the second axis (Y) is substantially perpendicular to the first axis (X). The first input unit 70 further has a first shaft section 72 extending from the first bevel gear section 71 along the second axis (Y) and outwardly of the housing 10 through the intermediate housing part 13.

The second input unit 80 is secured to the housing 10, is rotatable about the second axis (Y), is adapted to be coupled to the second power source 300, and has a second bevel gear section 81 extending into the gear meshing space 600 and meshing with the first and second bevel gears 40, 50. The second input unit 80 further has a second shaft section 82 extending from the second bevel gear section 81 along the second axis (Y) and outwardly of the housing 10 through the intermediate housing part 13. In this embodiment, the first and second input units 70,80 are disposed at diametrically opposite positions relative to the first axis (X), and drive the first and second bevel gears 40, 50 to rotate simultaneously in opposite directions in a manner to be described hereinafter.

The first needle bearing 90 is disposed between the first gear mounting portion 21 of the first output shaft 20 and the lower housing part 12 of the housing 10. The second needle bearing 100 is disposed between the first and second gear mounting portions 21, 300 of the first and second output shafts 20, 30. The third needle bearing 110 is disposed between the second gear mounting portion 300 and the upper housing part 11 of the housing 10.

The first ball bearings 120 are disposed between the intermediate housing part 13 of the housing 10 and the first shaft section 72 of the first input unit 70. The second ball bearings 121 are disposed between the intermediate housing part 13 and the second shaft section 82 of the second input unit 80.

The first one-way clutch 130 is adapted for coupling the first shaft section 72 of the first input unit 70 to the first power source 200. The second one-way clutch 140 is adapted for coupling the second shaft section 82 of the second input unit 80 to the second power source 300.

In this embodiment, the first and second one-way clutches 130, 140 are ratchet-type one-way clutches. When the rotation speed of the first power source 200 is larger than that of the first shaft section 72 of the first input unit 70, the first one-way clutch 130 connects the first power source 200 to the first shaft section 72. On the other hand, when the rotation speed of the first power source 200 is not larger than that of the first shaft section 72, the first one-way clutch 130 disconnects the first power source 200 from the first shaft section 72. Likewise, when the rotation speed of the second power source 300 is larger than that of the second shaft section 82 of the second input unit 80, the second one-way clutch 140 couples the second power source 300 to the second shaft section 82. On the other hand, when the rotation speed of the second power source 300 is not larger than that of the second shaft section 82, the second one-way clutch 140 disconnects the second power source 300 from the second shaft section 82.

When the first and second power sources 200, 300 are activated to drive the first and second input units 70, 80 via the first and second one-way clutches 130, 140 so as to rotate in opposite directions about the second axis (Y), the first and second bevel gears 40, 50 will be driven by the first and second bevel gear sections 71, 81 to rotate simultaneously in opposite directions about the first axis (X), thereby resulting in rotation of the first and second output shafts 10, 20 in the opposite directions about the first axis (X) and in corresponding rotation of upper and lower rotors (not shown) of the twin-rotor helicopter that are coupled to the first and second output shafts 10, 20 so as to result in flight of the twin-rotor helicopter.

In case of failure of one of the first and second power sources 200, 300, since the other one of the first and second power sources 200, 300 is still able to drive the respective input unit 70, 80, the first and second bevel gears 40, 50 can still be driven to rotate in the opposite directions about the first axis (X) so as to result in corresponding rotation of the first and second output shafts 20, 30 and the upper and lower rotors (not shown) that are connected thereto, thereby permitting safe landing of the twin-rotor helicopter even when one-half of the power is lost due to failure of one of the first and second power sources 200, 300.

While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

1. A dual-power transmission device for a twin-rotor helicopter, said dual-power transmission device being adapted to be coupled to first and second power sources and comprising: a housing; a first output shaft having a first gear mounting portion secured rotatably in said housing and a first rotor coupling portion extending from said first gear mounting portion and outwardly of said housing, said first output shaft being rotatable about a first axis; a second output shaft disposed to surround said first rotor coupling portion of said first output shaft and having a second gear mounting portion secured rotatably in said housing and a second rotor coupling portion extending from said second gear mounting portion and outwardly of said housing, said second output shaft being rotatable about the first axis; a first bevel gear mounted on and rotatable coaxially with said first gear mounting portion; a second bevel gear mounted on and rotatable coaxially with said second gear mounting portion; first, second and third thrust bearings, said first thrust bearing being disposed between said housing and said first bevel gear, said second thrust bearing being disposed between said first and second gear mounting portions, said third thrust bearing being disposed between said housing and said second bevel gear, said first, second and third thrust bearings cooperating to position said first and second bevel gears in said housing such that said first and second bevel gears are spaced apart from each other along the first axis and form a gear meshing space therebetween; a first input unit secured to said housing, rotatable about a second axis that intersects the first axis, adapted to be coupled to the first power source, and having a first bevel gear section extending into said gear meshing space and meshing with said first and second bevel gears; and a second input unit secured to said housing, rotatable about the second axis, adapted to be coupled to the second power source, and having a second bevel gear section extending into said gear meshing space and meshing with said first and second bevel gears.
 2. The dual-power transmission device as claimed in claim 1, wherein: said first gear mounting portion has a diameter larger than that of said first rotor coupling portion, thereby configuring said first output shaft with an annular shoulder at a junction of said first gear mounting portion and said first rotor coupling portion; said first gear mounting portion is formed with a first gear mounting flange that extends in radial outward directions relative to the first axis; said second gear mounting portion has one end proximate to said annular shoulder of said first output shaft and formed with a second gear mounting flange that extends in radial outward directions relative to the first axis; said first bevel gear is mounted on said first gear mounting flange; and said second bevel gear is mounted on said second gear mounting flange.
 3. The dual-power transmission device as claimed in claim 2, wherein: said housing has a first housing surface confronting said first bevel gear, and a second housing surface confronting said second bevel gear; said first thrust bearing is disposed between said first housing surface and said first bevel gear; said second thrust bearing is disposed between said first and second gear mounting flanges; and said third thrust bearing is disposed between said second housing surface and said second bevel gear.
 4. The dual-power transmission device as claimed in claim 3, wherein said housing includes a lower housing part formed with said first housing surface, an upper housing part formed with said second housing surface, and an intermediate housing part disposed between and coupled to said lower and upper housing parts, said first and second rotor coupling portions extending outwardly of said housing through said upper housing parts, said first and second input units extending outwardly of said housing through said intermediate housing part.
 5. The dual-power transmission device as claimed in claim 1, further comprising: a first needle bearing disposed between said first gear mounting portion and said housing; a second needle bearing disposed between said first and second gear mounting portions; and a third needle bearing disposed between said second gear mounting portion and said housing.
 6. The dual-power transmission device as claimed in claim 1, wherein said first input unit further has a first shaft section extending from said first bevel gear section along the second axis and outwardly of said housing, and said second input unit further has a second shaft section extending from said second bevel gear section along the second axis and outwardly of said housing, said dual-power transmission device further comprising a first ball bearing disposed between said housing and said first shaft section, and a second ball bearing disposed between said housing and said second shaft section.
 7. The dual-power transmission device as claimed in claim 6, further comprising a first one-way clutch adapted for coupling said first shaft section to the first power source, and a second one-way clutch adapted for coupling said second shaft section to the second power source.
 8. The dual-power transmission device as claimed in claim 1, wherein the second axis is substantially perpendicular to the first axis.
 9. The dual-power transmission device as claimed in claim 1, wherein said first and second input units are disposed at diametrically opposite positions relative to the first axis, and drive said first and second bevel gears to rotate simultaneously in opposite directions. 